1. Field of the Invention
This invention relates to an orthopedic support device, specifically a rear strut stabilized, derotational knee brace which may be used for prophylactic, functional and rehabilitative applications.
2. Background Information
Generally knee braces may be classified according to the function they perform. Prophylactic knee braces are used to reduce the likelihood of injury during activities, particularly sports, in which high loads are placed on the knee joint. Usually, an objective of prophylactic knee braces is to provide some support for the joint without unduly restricting movement, thus reducing the risk of injury to a normal knee joint. Functional knee braces are used to support and stabilize injured joints, and hence, provide the strongest reinforcement for the knee. They often prohibit certain movements. Rehabilitative knee braces are used to support previously injured joints and are used extensively during post operative and rehabilitation periods. Their designs generally lie between prophylactic and functional braces in the amount of support they provide, and the degree of restriction they impose on joint movement is usually adjustable to provide only a specific range of desired motion.
Prophylactic supports for the knee joint include wraps of adhesive or elastic tape and reinforced neoprene sleeves. These devices, however, do not provide the support generally required. Prophylactic knee braces have been designed as single hinged vertical members placed laterally on one side of the leg and held by cuffs and straps to the thigh and the leg. Since the anatomy in the knee region is naturally offset, the fixation on one side cannot support the brace effectively. These braces tend to slip, thus exerting undue forces acting against the natural kinematics on the knee joint, and also concentrate forces laterally on the knee, which in some cases, increases the risk of medial collateral ligament or anterior cruciate ligament injury. Several studies have demonstrated the ineffectiveness of such braces in preventing knee injury and in some cases, have demonstrated an increase in foot and ankle injuries as well. This may be due to the slippage of the brace which may cause interference with normal kinematic operation of the knee. This results in fatigue of the thigh and leg muscles, increasing the strain on knee ligaments and the knee joint, thus increasing the risk of injury. In addition, the medial collateral ligament can be preloaded by a lateral brace, increasing the probability of a medial collateral ligament rupture. The bunching up of the support materials in the popliteal space behind the knee, in braces which utilize "fillers" between parts, further contributes to this problem.
Functional knee braces typically have medial and lateral rigid supports for the knee joint. Many of these devices have complicated hinge structures designed to accommodate for the femoral rollback which occurs upon flexion of the knee joint. Some of these braces use rigid molded thigh and leg cuffs to support the hinged lateral and medial support members. Other braces have utilized spiral structures and straps to connect the thigh and leg cuffs. These devices have not proven as effective as desired to protect against a knee injury and to support and stabilize an unstable knee or protect an injured knee. The major disadvantage of these rigid braces is slippage due to the conical shape of the lower extremity. With slippage, even a well designed brace can alter the kinematics of the knee and increase the risk of injury. Altering the normal motion of the knee also causes muscle fatigue, thus, increasing risk of injury. These braces with rigid molded cuffs which capture the knee, prevent the musculature surrounding the knee from effectively absorbing the forces induced around the joint. Existing functional braces have not been proven to effectively control anterior instability at high loads.
Another type of knee brace uses an adjustable rigid or semi-rigid member encircling the knee joint which clamps lateral and medial pads against the knee joint. The proper operation of such braces depends on the exact fit on a specific knee, and therefore must be custom fitted. They are also bulky and generally more expensive. These devices tend to unduly restrict motion of the knee joint. Because of their more complex nature and bulkiness, interference with normal knee operation is higher if the hinge is misaligned.
There remains a need therefore for an improved knee brace for prophylactic, functional and rehabilitative applications.
There is also a need for such an improved knee brace which provides the required support for the knee without undue restriction on the natural movement of the joint.
There is also a need for such an improved knee brace which does not increase the risk of injury.
There is a further need for such an improved knee brace which distributes the load to the fleshy parts of the thigh and leg.
There is yet another need for such an improved knee brace which reduces both shear and torsion forces applied to the knee.
There is still another need for such an improved knee brace which does not slip out of position or bind.
There is an additional need for such an improved knee brace which is light weight and easy to apply and remove.